istio服务网格初探

Istio是现目前流行的服务网格（service mess）方案。对比spring cloud微服务

减少开发团队的压力，运维来做
解藕，代码中不在依赖各类组件
spring cloud 依赖包太大，啥事不干，几十MB
Istio缺点：需要对k8s熟悉，配置起来较麻烦
Istio有些功能无法实现的，如：分布式事务、配置中心

本例主要实现流量控制
参考官网教程https://istio.io/latest/docs/setup/getting-started/
安装环境 ubuntu20 k8s-1.19.2 istio-1.8.0
安装

curl -L https://istio.io/downloadIstio | sh -
cd istio-1.8.0

加入到环境变量vi ~/.profile

export PATH="$PATH:/home/your_home/istio-1.8.0/bin"

Install Istio

istioctl install --set profile=demo -y

创建tomcat/jetty二个空服务

kubectl apply -f app.yaml

app.yaml

apiVersion: v1
kind: Namespace
metadata:
  name: istio-example

---
# 暴露外网使用
apiVersion: v1
kind: Service
metadata:
  name: app-svc
  namespace: istio-example
spec:
  selector:
    app: web
  type: NodePort
  ports:
  - port: 80
    targetPort: 8080
    nodePort: 30002

---

apiVersion: v1
kind: Service
metadata:
  name: jetty-svc
  namespace: istio-example
spec:
  selector:
    server: jetty
  ports:
  - port: 80
    targetPort: 8080

---

apiVersion: v1
kind: Service
metadata:
  name: tomcat-svc
  namespace: istio-example
spec:
  selector:
    server: tomcat
  ports:
  - port: 80
    targetPort: 8080

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: jetty-deployment
  namespace: istio-example
  labels:
    app: web
    server: jetty
spec:
  replicas: 1
  selector:
    matchLabels:
      app: web
      server: jetty
  template:
    metadata:
      labels:
        app: web
        server: jetty
    spec:
      containers:
      - name: jetty
        image: jetty:latest
        ports:
        - containerPort: 8080

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomcat-deployment
  namespace: istio-example
  labels:
    app: web
    server: tomcat
spec:
  replicas: 1
  selector:
    matchLabels:
      app: web
      server: tomcat
  template:
    metadata:
      labels:
        app: web
        server: tomcat
    spec:
      containers:
      - name: tomcat
        image: tomcat:latest
        ports:
        - containerPort: 8080

手工注入

kubectl apply -f <(istioctl kube-inject -f app.yaml)

查看注入结果， READY需2/2，实际上多注入了一个sidecar

$ kubectl get pods -n istio-example
NAME                                READY   STATUS    RESTARTS   AGE
jetty-deployment-7444466f5d-jb2gn   2/2     Running   0          107s
tomcat-deployment-8d576b9fb-thzvh   2/2     Running   0          107s

创建网关

kubectl apply -f gateway.yaml

gateway.yaml

apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  namespace: istio-example
  name: istio-gateway
spec:
  selector:
    istio: ingressgateway # use istio default controller
  servers:
  - port:
      number: 80
      name: http
      protocol: HTTP
    hosts:
    - "*"

创建VirtualSerice。分配80%的流量到jetty，20%到tomcat

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  namespace: istio-example
  name: app-vs
spec:
  hosts:
  - "*"
  gateways:
  - istio-gateway
  http:
  - route:
    - destination:
        host: jetty-svc
      weight: 80
    - destination:
        host: tomcat-svc
      weight: 20

导出Istio的入口网关（可理解为spring cloud gateway），NodePort端口

kubectl patch svc -n istio-system istio-ingressgateway -p '{"spec": {"type": "NodePort"}}'

查询nodePort

kubectl -n istio-system get service istio-ingressgateway -o jsonpath='{.spec.ports[?(@.name=="http2")].nodePort}'

导出后，通过http://192.168.1.30:nodePort访问网站

Kiali dashboard。kiali地址http://192.168.1.30:20001/kiali

istioctl dashboard kiali --address 192.168.1.30

效果图

来源：oschina

链接：https://my.oschina.net/u/160697/blog/4770858

标签

Tomcat

jetty

YAML